Self-adaptive spinning cake end finding method and mechanism based on laser ranging and negative pressure feedback

Abstract

The invention relates to the technical field of textile machinery automation, and discloses a spinning cake self-adaptive end finding mechanism based on laser contour scanning and negative pressure feedback. Comprising a station platform used for bearing a spinning cake, a driving device used for driving the spinning cake to rotate around the axis of the spinning cake, a suction nozzle used for sucking yarn ends, a longitudinal moving module used for controlling the suction nozzle to move front and back in the radial direction of the spinning cake, and a clamping mechanism used for clamping yarn. According to the invention, the laser distance measuring sensor rotates along with the spinning cake to continuously collect surface distance data, the upper computer constructs a circumferential contour oscillogram based on the data, and by identifying the step mutation characteristics of the distance data and accurately positioning the phase angle where the thread end is located, targeted fixed-point adsorption is realized, blind rotation attempts are avoided, and the thread end finding time is greatly shortened; and the laser irradiation track accurately corresponds to the suction nozzle adsorption track, so that the positioning accuracy is further improved, and accurate alignment of the suction nozzle and the thread residue is ensured.

Description

Technical Field

[0001] This invention relates to the field of textile machinery automation technology, specifically to a method and mechanism for adaptive yarn cake finding based on laser ranging and negative pressure feedback. Background Technology

[0002] In automated hosiery production, automatically and reliably locating the yarn end from the yarn package ("end finding") is a key bottleneck in achieving automated yarn sampling and knotting. Existing technologies mostly employ end-finding mechanisms integrated into automated equipment, but these have significant limitations. The closest existing technology is the "knotting device" (CN109487353A) from Hangzhou Junchen Robotics Co., Ltd., which integrates end-picking functionality. However, this device suffers from the following core problems: 1. Low search efficiency: The organization does not know the exact location of the yarn end on the circumference and must rely on the continuous rotation of the yarn cake to try their luck, resulting in a long search time.

[0003] 2. Energy waste: Continuing to operate the high vacuum negative pressure without aligning the yarn end results in a huge waste of compressed air.

[0004] 3. Lack of feature recognition: It cannot identify the microscopic morphological features (such as protrusions or disordered layers) at the yarn ends, and has poor adaptability to difficult yarn cakes.

[0005] Currently, the industry lacks a yarn cake finding mechanism that integrates non-contact positioning, adaptive adsorption, and real-time feedback, which makes it difficult to meet the automation, high precision, and high adaptability requirements of modern textile production. There is an urgent need for a new adaptive finding method and mechanism. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of low efficiency, high energy consumption, and inaccurate yarn head positioning caused by "blind adsorption" in existing technologies, as well as the inability to accurately position the yarn head by simply relying on distance. This invention uses laser contour scanning technology to first establish a circumferential distance waveform diagram on the surface of the yarn cake, intelligently identify the phase angle of the yarn head, and achieve targeted point capture.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a yarn cake adaptive head-finding mechanism based on laser contour scanning and negative pressure feedback, comprising: a workstation platform for carrying the yarn cake, a drive device for driving the yarn cake to rotate around its own axis, a suction nozzle for adsorbing yarn ends, a longitudinal movement module for controlling the suction nozzle to move back and forth radially along the yarn cake, a clamping mechanism for holding the yarn, a laser rangefinder for collecting distance data on the surface of the yarn cake, a negative pressure feedback system for monitoring the adsorption state, and a host computer for coordinating and controlling all components; The host computer has a built-in contour construction and feature recognition module, and is configured to execute the following control logic: Step 1: Before the suction nozzle performs the suction action, the host computer sends a control signal to the drive device, which drives the silk cake to rotate at least one revolution. At the same time, the host computer controls the laser range sensor to continuously collect distance data on the outer circumference surface of the silk cake at a preset frequency. Based on the collected distance data and the silk cake rotation angle at the corresponding sampling time, the contour construction and feature recognition module constructs a circumferential contour waveform of the silk cake surface. Step 2: The feature recognition module performs data analysis on the circumferential contour waveform diagram. By identifying abrupt changes in distance data, it locates and calculates the phase angle of the yarn cake where the yarn end is located. Step 3: The host computer sends a positioning signal to the drive device, which drives the yarn cake to rotate to the phase angle position and controls the yarn cake to remain stationary or in a low-speed creeping state. Then, the host computer sends a displacement signal to the longitudinal translation module, which drives the suction nozzle to advance to the target position. This target position is calculated based on the measured distance of the laser rangefinder at the phase angle and is the optimal adsorption position of the suction nozzle. Finally, the host computer controls the negative pressure feedback system to start, so that the suction nozzle performs negative pressure adsorption.

[0008] The adaptive head-finding method for silk cake based on laser contour scanning and negative pressure feedback includes the following steps: a) Contour scanning steps: Start the drive device to drive the silk cake to rotate around its own axis, and simultaneously start the laser range sensor. The laser range sensor continuously collects the distance data on the surface of the silk cake during the process of the silk cake rotating once, and establishes the mapping relationship between the rotation angle of the silk cake and the corresponding distance data. b) Feature localization step: The mapping relationship is processed to calculate the distance difference between adjacent sampling points. When a region with a step change in distance value is detected, the region is determined to be the location of the yarn end, and the target phase angle is calculated based on the rotation angle corresponding to the region. c) Positioning step: Send control commands to the drive device, which drives the yarn cake to rotate, so that the yarn end rotates to the preset reference position, thereby aligning the nozzle with the yarn end. d) Adaptive adsorption step: Start the longitudinal movement module, which drives the suction nozzle to move forward until the distance between the suction nozzle and the yarn surface reaches the preset value. Then, turn on the negative pressure system to make the suction nozzle perform the adsorption action. e) Feedback confirmation step: The airflow changes in the negative pressure pipeline are monitored in real time through the negative pressure feedback system. When a sudden drop in airflow speed is detected, it is determined that the yarn end has been successfully sucked into the nozzle, and the clamping mechanism is then triggered to close to clamp the yarn.

[0009] Preferably, the specific logic of the feature recognition module of the host computer to identify the phase angle of the yarn end is as follows: traverse the distance data in the circumferential contour waveform diagram and calculate the distance difference D between two adjacent sampling points; preset a threshold that matches the yarn thickness, and when the distance difference D of multiple consecutive sampling points exceeds the threshold, determine that the area is the overlap of the yarn end, and then determine the phase angle of the yarn cake corresponding to the overlap.

[0010] Preferably, the negative pressure feedback system includes a digital airflow sensor and a proportional solenoid valve, both connected in series in the negative pressure air path of the suction nozzle. The digital airflow sensor is used to collect airflow velocity data in the air path in real time and transmit it to the host computer. After receiving a signal of a sudden drop in airflow velocity, the host computer determines that the yarn end has been successfully adsorbed. At the same time, the host computer sends an adjustment signal to the proportional solenoid valve to control the proportional solenoid valve to reduce the valve opening, thereby reducing the suction force in the negative pressure air path and avoiding excessive extraction of yarn, which could cause yarn breakage or damage.

[0011] Preferably, the laser rangefinder is fixedly installed on the side of the suction nozzle, and the laser emission path of the laser rangefinder is parallel to the central axis of the suction nozzle; the laser irradiation point of the laser rangefinder is located on the tangent direction of the silk cake at the edge of the suction inlet of the suction nozzle, ensuring that the scanning trajectory of the laser rangefinder and the adsorption trajectory of the suction nozzle correspond precisely in space, thereby improving the head-finding and positioning accuracy.

[0012] This invention provides a method and mechanism for adaptive wire cake finding based on laser ranging and negative pressure feedback. It has the following beneficial effects: 1. This invention uses a laser rangefinder to continuously collect surface distance data as the yarn cake rotates. The host computer constructs a circumferential contour waveform based on the data. By identifying the step change characteristics of the distance data, the phase angle of the yarn end is accurately located, achieving targeted adsorption and avoiding blind rotation attempts, thus significantly shortening the yarn end finding time. The laser irradiation trajectory and the suction nozzle adsorption trajectory are precisely correlated, further improving the positioning accuracy and ensuring that the suction nozzle and the yarn end are accurately aligned.

[0013] 2. This invention, through its feature recognition module, can adapt to yarns of different thicknesses and materials by adjusting the distance difference threshold; the non-contact design of laser scanning and feature recognition is also effective for difficult yarn cakes with tightly wrapped threads and hidden ends, and can complete the head finding without manual intervention, adapting to the head finding needs of yarn cakes of different specifications, thus improving the versatility and reliability of the technology.

[0014] 3. This invention uses a negative pressure feedback system to monitor changes in airflow in the gas path in real time through a digital airflow sensor. Once adsorption is successful, the clamping mechanism is immediately triggered to close, while the opening of the negative pressure valve is reduced to decrease the suction force, thus avoiding energy waste caused by continuous high vacuum. The real-time feedback mechanism can accurately judge the adsorption status. If adsorption fails, it can automatically trigger a second head search, improving the reliability of the operation and reducing manual intervention.

[0015] 4. This invention uses a longitudinal movement module to calculate the optimal advance position of the suction nozzle based on the actual laser measurement distance, ensuring that the distance between the suction nozzle and the thread end is appropriate and improving the adsorption success rate. After successful adsorption, the suction force is dynamically adjusted by a proportional solenoid valve, which avoids excessive suction force that may cause yarn breakage and maintains stable adsorption of the thread end, thus balancing adsorption reliability and yarn protection and reducing production losses. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a flowchart illustrating the mechanism control of the present invention. Figure 3 This is a flowchart of the adaptive head-finding method of the present invention; Figure 4 This is a flowchart of the phase angle recognition logic of the present invention; Figure 5 This is a flowchart of the negative pressure feedback system of the present invention; Figure 6 This is a flowchart illustrating the coordination process between the laser sensor and the suction nozzle in this invention. In the diagram: 21. Suction nozzle; 22. Longitudinal movement module; 23. Laser rangefinder sensor; 24. Clamping mechanism; 25. Digital airflow sensor. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0019] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] Example 1 A preferred embodiment of the adaptive wire cake finding method and mechanism based on laser ranging and negative pressure feedback provided by this invention is as follows: Figure 1-6 As shown: The adaptive yarn head finding mechanism based on laser contour scanning and negative pressure feedback includes: a workstation platform for carrying the yarn, a drive device for driving the yarn to rotate around its own axis, a suction nozzle 21 for adsorbing yarn ends, a longitudinal movement module 22 for controlling the suction nozzle 21 to move back and forth along the radial direction of the yarn, a clamping mechanism 24 for clamping the yarn, a laser rangefinder 23 for collecting distance data on the surface of the yarn, a negative pressure feedback system for monitoring the adsorption state, and a host computer for overall control of the various components. The host computer has a built-in contour construction and feature recognition module, and is configured to execute the following control logic: Step 1: Before the suction nozzle 21 performs the suction action, the host computer sends a control signal to the drive device, and the drive device drives the silk cake to rotate at least one revolution; at the same time, the host computer controls the laser range sensor 23 to continuously collect distance data on the outer circumferential surface of the silk cake at a preset frequency. Based on the collected distance data and the silk cake rotation angle at the corresponding sampling time, the contour construction and feature recognition module constructs a circumferential contour waveform of the silk cake surface. Step Two: The feature recognition module analyzes the circumferential contour waveform. By identifying abrupt changes in distance data, it locates and calculates the phase angle of the yarn end on the yarn cake. The abrupt changes in distance data are determined using the formula for the distance difference between adjacent sampling points. In the formula For the first The sampling point and the first Distance difference between sampling points (unit: mm) For the laser rangefinder sensor in the first Distance data of the silk cake surface collected at each sampling time (unit: mm). For the laser rangefinder sensor in the first Distance data of the silk cake surface collected at each sampling time (unit: mm). For sampling point number ( ≥2, The target phase angle is obtained through the formula. In the formula The target phase angle (unit: °) corresponding to the yarn end. The rotation angle of the silk cake corresponding to the first sampling point in the continuous mutation region (unit: °). This is the sequence number of the first sampling point in the continuous mutation region. This is the sequence number of the last sampling point in the continuous mutation region. The total number of sampling points for one revolution of the silk cake ( , Preset the sampling frequency (Hz) for the laser rangefinder sensor. (The time it takes for the silk cake to rotate once (s)); Step 3: The host computer sends a positioning signal to the drive device, which rotates the yarn cake to the phase angle position and controls the yarn cake to remain stationary or in a low-speed creeping state. Subsequently, the host computer sends a displacement signal to the longitudinal translation module 22, which drives the suction nozzle 21 to the target position. This target position is based on the measured distance from the laser rangefinder 23 at the phase angle, calculated using the formula... The calculation shows that the optimal suction position for nozzle 21 is determined by the formula. The target advance position of the suction nozzle along the radial direction of the silk cake (unit: mm, with the initial position of the longitudinal movement module as the origin). For the laser rangefinder at the target phase angle Measured distance data at the location (unit: mm). The optimal distance between the suction nozzle and the yarn surface is preset (unit: mm); finally, the host computer controls the negative pressure feedback system to start, so that the suction nozzle 21 performs negative pressure adsorption action.

[0021] Example 2 Please see Figures 1-6 Furthermore, based on Example 1, the following adaptive head-finding method for silk cake based on laser contour scanning and negative pressure feedback is obtained, including the following steps: a) Contour scanning steps: Start the drive device to drive the silk cake to rotate around its own axis, and simultaneously start the laser range sensor 23. The laser range sensor 23 continuously collects the distance data on the surface of the silk cake during the process of the silk cake rotating once, and establishes the mapping relationship between the rotation angle of the silk cake and the corresponding distance data. b) Feature localization step: Data processing of the mapping relationship, using formulas... Calculate the distance difference between adjacent sampling points, and preset a threshold that matches the yarn thickness. (in the formula) The threshold for determining the distance difference (unit: mm). For safety factors (value range 1.2~1.5), The distance difference between multiple consecutive sampling points is measured when the yarn filament diameter or equivalent ply thickness (unit: mm) is detected. All exceeded the threshold When a region experiences a sudden change in distance value, that region is identified as the location of the yarn end, and the formula is used based on the corresponding rotation angle of that region. Calculate the target phase angle; c) Positioning step: Send a control command to the drive device, which drives the yarn cake to rotate, so that the yarn end rotates to the preset reference position, thereby aligning the suction nozzle 21 with the yarn end. d) Adaptive adsorption step: Start the longitudinal movement module 22, which drives the suction nozzle 21 to move forward until the distance between the suction nozzle 21 and the yarn surface reaches the preset value. Then, turn on the negative pressure system to make the suction nozzle 21 perform the adsorption action. e) Feedback Confirmation Step: Real-time monitoring of airflow changes in the negative pressure pipeline is achieved through a negative pressure feedback system, and the formula is used to confirm the feedback. Calculate the rate of change of airflow velocity (in the formula) This represents the real-time rate of change of airflow velocity (unitless). The values ​​are real-time data collected by a digital airflow sensor during the negative pressure adsorption process (unit: m / s). The initial airflow velocity (in m / s) of the negative pressure air path before adsorption. ( When the airflow speed drops sharply (the threshold value is 0.3~0.6), it is determined that the yarn end has been successfully sucked into the suction nozzle 21, and the clamping mechanism 24 is then triggered to close to clamp the yarn.

[0022] Example 3 Please see Figures 1-6 Furthermore, based on Example 1, the following logic is obtained: the feature recognition module of the host computer identifies the phase angle of the yarn end as follows: traverse the distance data in the circumferential contour waveform diagram and calculate the distance difference between two adjacent sampling points; preset a threshold that matches the yarn thickness; when the distance difference of multiple consecutive sampling points exceeds the threshold, determine that the area is the overlap of the yarn end, and then determine the phase angle of the yarn cake corresponding to the overlap.

[0023] The negative pressure feedback system includes a digital airflow sensor 25 and a proportional solenoid valve, both connected in series in the negative pressure air path of the suction nozzle 21. The digital airflow sensor 25 is used to collect airflow velocity data in the air path in real time and transmit it to the host computer. After receiving a signal of a sudden drop in airflow velocity, the host computer determines that the yarn end has been successfully adsorbed. At the same time, the host computer sends an adjustment signal to the proportional solenoid valve, which adjusts the pressure according to the formula. and Control the proportional solenoid valve to reduce the valve opening (where) The valve opening degree after adjustment by the proportional solenoid valve (unit: %). The valve opening at the initial adsorption stage (unit: %, preset to 80%~100%). This is the opening adjustment coefficient (range 0.2~0.4). The valve flow coefficient after adjustment (unit: m³ / h). This is the rated flow coefficient (unit: m³ / h) when the valve is at its maximum opening. The maximum opening of the proportional solenoid valve (unit: %, fixed at 100%) is used to reduce the suction in the negative pressure air circuit and avoid excessive extraction of yarn, which could cause yarn breakage or damage.

[0024] The laser rangefinder 23 is fixedly installed on the side of the suction nozzle 21. The laser emission path of the laser rangefinder 23 is parallel to the central axis of the suction nozzle 21. The laser irradiation point of the laser rangefinder 23 is located on the tangent of the silk cake at the edge of the suction inlet of the suction nozzle 21, ensuring that the scanning trajectory of the laser rangefinder 23 and the adsorption trajectory of the suction nozzle 21 are accurately corresponded in space, thereby improving the head finding and positioning accuracy.

[0025] During use, the laser rangefinder 23 and the suction nozzle 21 are precisely aligned, and the laser irradiation point corresponds to the suction trajectory of the nozzle, ensuring spatial consistency between the scanning data and the suction position. During the rotation of the yarn cake, the laser sensor continuously collects distance data and constructs a circumferential contour waveform. Due to the sudden change in thickness at the yarn end overlap, the distance data will show a step change. The feature recognition module calculates the difference between adjacent sampling points and compares the threshold to accurately locate the sudden change area, and then calculates the target phase angle to achieve non-contact, high-precision positioning of the yarn end with a positioning error of ≤±0.5mm.

[0026] The longitudinal movement module 22 calculates the optimal advance position of the suction nozzle based on the measured distance of the laser sensor, ensuring that the distance between the suction nozzle and the thread end is matched and improving the adsorption success rate. After the negative pressure system is started, the proportional solenoid valve has a large initial opening (80%-100%), providing sufficient suction to adsorb the thread end. When the airflow sensor detects a sudden drop in airflow speed (thread end blocking the suction nozzle), the host computer determines that the adsorption is successful and immediately controls the proportional solenoid valve to reduce the opening, reducing the suction to just maintain the level of thread end adsorption, avoiding excessive extraction that could cause yarn breakage or damage.

[0027] The negative pressure feedback system monitors the adsorption status in real time through an airflow sensor, solving the problem of "no feedback and blind operation" in traditional adsorption. When adsorption is detected to be successful, the clamping mechanism is immediately triggered to close, forming a closed-loop control of "positioning-adsorption-feedback-clamping" to ensure the reliability of the head-finding process. If adsorption fails (such as when no sudden drop in airflow is detected within a preset time), the host computer can automatically trigger a second scan and adsorption process to improve the head-finding success rate.

[0028] By using parameterized configuration (sampling frequency, threshold, suction strength, nozzle spacing, etc.), this method and mechanism can be adapted to yarn cakes of different diameters (50-300mm) and winding densities, as well as yarns of different thicknesses (0.1-1mm) and materials (chemical fiber, cotton, wool). The high sampling frequency and wide measurement range of the laser sensor ensure the contour scanning accuracy of yarn cakes of different specifications. The adjustability of the threshold and suction strength allows it to match the head-finding requirements of yarns of different thicknesses.

[0029] In summary, this invention utilizes a laser rangefinder sensor for "topography mapping." The sensor's application is expanded from simple "distance measurement" to "feature recognition," locating the thread end by analyzing microscopic changes in the distance waveform on the silk cake surface.

[0030] This invention uses a "distance mutation detection algorithm" to replace the traditional PID following algorithm as the core logic for finding the end of the wire, thus solving the problem of identifying irregularly tangled or hidden wire ends.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A silk cake adaptive head-finding mechanism based on laser contour scanning and negative pressure feedback, characterized in that, include: The components include a workstation platform for carrying the yarn cake, a drive device for driving the yarn cake to rotate around its own axis, a suction nozzle (21) for adsorbing yarn ends, a longitudinal movement module (22) for controlling the suction nozzle (21) to move back and forth along the radial direction of the yarn cake, a clamping mechanism (24) for clamping the yarn, a laser rangefinder (23) for collecting distance data on the surface of the yarn cake, a negative pressure feedback system for monitoring the adsorption state, and a host computer for coordinating and controlling all components.

2. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 1, characterized in that, The host computer has a built-in contour construction and feature recognition module, which is configured to perform contour scanning, feature localization, fixed-point alignment and adsorption control, and coordinate the orderly operation of each component.

3. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 2, characterized in that, The contour construction logic is as follows: Before the suction nozzle (21) performs the adsorption action, the host computer sends a control signal to the drive device, and the drive device drives the silk cake to rotate at least one revolution. At the same time, the host computer controls the laser ranging sensor (23) to continuously collect distance data of the outer circumferential surface of the silk cake at a preset frequency. Based on the collected distance data and the silk cake rotation angle at the corresponding sampling time, the contour construction and feature recognition module constructs the circumferential contour waveform of the silk cake surface.

4. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 2, characterized in that, The feature localization logic is as follows: the feature recognition module performs data analysis on the circumferential contour waveform diagram, and locates and calculates the phase angle of the yarn cake where the yarn end is located by identifying the abrupt change characteristics of the distance data.

5. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 2, characterized in that, The positioning and adsorption control logic is as follows: the host computer sends a positioning signal to the drive device, the drive device drives the silk cake to rotate to the phase angle position, and controls the silk cake to remain stationary or in a low-speed creeping state.

6. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 2, characterized in that, The specific logic of the feature recognition module for recognizing the phase angle and adsorption control is as follows: the host computer sends a displacement signal to the longitudinal movement module (22), and the longitudinal movement module (22) drives the nozzle (21) to advance to the target position. The target position is calculated based on the measured distance of the laser range sensor (23) at the phase angle, which is the optimal adsorption position of the nozzle (21). Finally, the host computer controls the negative pressure feedback system to start, so that the nozzle (21) performs the negative pressure adsorption action.

7. A method for adaptive head finding of a silk cake based on laser contour scanning and negative pressure feedback, characterized in that, Includes the following steps: a) Contour scanning steps: Start the drive device to drive the silk cake to rotate around its own axis, and simultaneously start the laser range sensor (23). The laser range sensor (23) continuously collects the distance data of the silk cake surface during the silk cake's rotation, and establishes the mapping relationship between the silk cake's rotation angle and the corresponding distance data. b) Feature localization step: The mapping relationship is processed to calculate the distance difference between adjacent sampling points. When a region with a step change in distance value is detected, the region is determined to be the location of the yarn end, and the target phase angle is calculated based on the rotation angle corresponding to the region. c) Positioning step: Send control command to drive device, drive device to rotate yarn cake, rotate yarn end to preset reference position, realize the alignment of nozzle (21) with yarn end position; d) Adaptive adsorption step: Start the longitudinal movement module (22), the longitudinal movement module (22) drives the suction nozzle (21) to move forward until the distance between the suction nozzle (21) and the yarn surface reaches the preset value, and then turn on the negative pressure system to make the suction nozzle (21) perform adsorption action; e) Feedback confirmation step: The airflow changes in the negative pressure pipeline are monitored in real time through the negative pressure feedback system. When a sudden drop in airflow speed is detected, it is determined that the yarn end has been successfully sucked into the suction nozzle (21), and then the clamping mechanism (24) is triggered to close to clamp the yarn.

8. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 1, characterized in that, The specific logic of the feature recognition module of the host computer to identify the phase angle of the yarn end is as follows: traverse the distance data in the circumferential contour waveform diagram and calculate the distance difference D between two adjacent sampling points; preset a threshold that matches the yarn thickness, and when the distance difference D of multiple consecutive sampling points exceeds the threshold, determine that the area is the overlap of the yarn end, and then determine the phase angle of the yarn cake corresponding to the overlap.

9. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 1, characterized in that, The negative pressure feedback system includes a digital airflow sensor (25) and a proportional solenoid valve, both of which are connected in series in the negative pressure air path of the suction nozzle (21). The digital airflow sensor (25) is used to collect airflow speed data in the air path in real time and transmit it to the host computer. After receiving a signal of a sudden drop in airflow speed, the host computer determines that the yarn end has been successfully adsorbed. At the same time, the host computer sends an adjustment signal to the proportional solenoid valve to control the proportional solenoid valve to reduce the valve opening, so as to reduce the suction force in the negative pressure air path and avoid excessive extraction of yarn, which could cause yarn breakage or damage.

10. The adaptive head-finding mechanism for the silk cake based on laser contour scanning and negative pressure feedback according to claim 1, characterized in that, The laser rangefinder (23) is fixedly installed on the side of the suction nozzle (21). The laser emission path of the laser rangefinder (23) is parallel to the central axis of the suction nozzle (21). The laser irradiation point of the laser rangefinder (23) is located on the tangent of the silk cake at the edge of the suction port of the suction nozzle (21), ensuring that the scanning trajectory of the laser rangefinder (23) and the adsorption trajectory of the suction nozzle (21) are accurately corresponded in space, thereby improving the head-finding and positioning accuracy.

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